You’ll likely run in to a little bit of trouble because you’re having to make explicit what would have been better for them to have inferred and when it’s made explicit like that, it will come across as very weird to people and they’ll probably have some trouble not taking it personally (even if they shouldn’t).

Some understanding of the general tenor of how this group talks would make for better ways to communicate what you want to say but as general advice, your proposed ways of addressing this seem like they’re on the right track in spirit but you’re phrasing them in ways that imply a note of contempt.

This is probably because you really do harbour some contempt for these guys given the way you described them, like calling them childish for example. If you actually want to express some of that animosity then your suggestions are probably fine but if you’re concerned about the “right” way to set these boundaries you might want to try and keep it neutral. This is also good if you don’t want to earn their contempt either which is probably advisable even if you don’t like them very much since you have to work with them and if they feel offended and hold a grudge it could risk spilling over in to the actual work.

I like your idea of saying outright that you’re not a talkative person, hopefully they’ll feel a little guilty about having forced you in to having to say that and will not try to drag you in to the conversation so much from then on. The additional bits around that concept don’t seem advisable, you don’t have to chastise them for not realising you don’t want to talk, that’s likely to be unproductive, the point is you don’t want to talk. Similarly the “and I hope you respect that” addition is good for being firm but also comes across a little aggressive, best deployed only if you’ve already made your wishes explicit and they’re clearly not respecting that.

Eating elsewhere, if that’s an option is great, it you can already opt for that do it, you can avoid even having to bring anything up and the physical separation makes questioning you about it really inconvenient. If they ask you about it later that’s when you can say you need time to unwind and that’s also by far the most socially acceptable and understandable reason that people are less likely to take personally. I don’t know if you resent the idea that your reasons have to be socially acceptable to these guys or should have to be massaged to avoid them taking things personally, but ask yourself this: do you want to teach them a lesson and demonstrate your contempt for them, or do you want to just be left alone to work and to continue to work effectively with them? Pragmatism over principle would make sense here.

If it gets to the point where you have to actually say to another adult, in a work environment, “leave me alone” then odds are it probably won’t even work and your coworkers are complete idiots that need to be fired. However if that’s really the case, saying that, even if it doesn’t work is probably good since at that point things are probably going to escalate and at least no one can say you did or said anything inappropriate.

In short, take the easiest route if possible and just eat somewhere else at lunch and redirect the conversation back to work if they keep talking to you during work. If you end up somehow having absolutely no other remaining options but to explicitly tell them you don’t want to talk be careful to communicate in a way so you only express this simple desire and don’t imply some sort of judgement or contempt towards them. Try to be nice about it.